Scientists Uncover Graphene Superlattices

The Hofstadter Butterfly Phenomenon. Credit: The University of Manchester

The first new type of quantum oscillation seen in 30 years has been reported recently thanks to researchers led by the University of Manchester. This process occurs when a magnetic field is applied to it and is the first of its kind to show up on the mesoscale. It also helps to shed light on the mysterious Hofstadter butterfly phenomenon.

Quantum oscillations are significant because they can be used to map properties of materials in the magnetic field. The study also demonstrates how it’s possible to tune the magnetic field relating to a heterostructure that’s made up of graphene and boron nitride in order to produce a whole range of different electronic materials.

Superlattices are created in graphene and interact with the magnetic field in a way that allows its oscillation to be tuned to make bands and gaps in its electronics structure. Basically. This means that the magnetic field can be used to tune the materials to be. However we need (i.e., metallic, conducting, or semi-conducting).

“Oscillatory quantum effects always present milestones in our understanding of materials properties. They are exceedingly rare,” says Andre Geim, a key member of the team and the 2010 Nobel Laureate. “It is more than 30 years of a new type of quantum oscillation was reported,” he added.

The research also sheds light on the Hofstadter butterfly phenomenon in which a fractal pattern seeks to describe the behavior of electrons found in magnetic fields. Original research is based on the electrons being Bloch electrons which do not interact with one another but move within the lattice within a periodic electric potential.

“Our work helps to demystify the Hofstadter butterfly. The complex fractal structure of the Hofstadter butterfly spectrum can be understood as simple Landau quantization in the sequence of new metals created by a magnetic field,” confirmed Professor Vladimir Falko, Director of the National Graphene Institute.